The objective of this study was to understand how and when dairy cattle will voluntarily use a water source that is located away from other resources, such as shaded feeding and lying areas, and how this use would affect behavioural and physiological indicators of heat stress. Twenty-four Holstein Friesian, non-lactating, dairy cows were used, with four animals tested simultaneously, half of which had access to a cow shower (n=12 with shower, n=12 control). Internal body temperature and behaviour, including shower use, were recorded 24h/d for five days during summer (mean temperature=25.3°C), whereas respiration rate and skin temperature were recorded between 10:00-18:00h. Dependent variables were compared with t-tests. Cattle spent 3.0±2.1h/d in the shower, and there was considerable variability between animals (range: 0.0-5.8h/d). Cows preferentially used the shower during the daytime, with 89%±12% of the time spent in the shower between 10:00-19:00h. Shower use increased with warmer weather by 0.3h for every 1°C increase in ambient temperature. Respiration rate and skin temperature did not differ between treatments (53±3.7 vs. 61±4.3 breaths/min and 35.0±0.3°C vs. 35.4±0.4°C in shower and control cows, respectively, P³0.16). In contrast, cows provided with a shower had lower (0.2±0.1°C) body temperature than control cows in the evening (18:00-21:00h; P£0.05), which is around the time when daily peak of body temperature occurred. Weather affected cattle time budgets and physiological responses in both treatments. Cows spent less time lying when heat load index (HLI) increased (P<0.001), but the total time spent lying, standing, and feeding did not differ between treatments (P=0.500, P=0.316, P=0.500, respectively). Cows also had higher respiration rate, skin temperature and body temperature as HLI increased (P<0.001), regardless of treatment. These data suggest that cattle, when given the opportunity, will make considerable use of a shower, thus alleviating some of the effects of heat load in summer.